Organic Chemistry : Help with Aldol Condensation

Study concepts, example questions & explanations for Organic Chemistry

varsity tutors app store varsity tutors android store

Example Questions

Example Question #652 : Organic Chemistry

Screen shot 2015 07 07 at 8.30.46 pm

Determine the major product of the given intramolecular aldol reaction.

Screen shot 2015 07 07 at 8.30.53 pm

Possible Answers:

III

IV

II

None of these

I

Correct answer:

II

Explanation:

Keep in mind the following principles: Cyclization is favored when a five/six-member ring may be formed. Addition at an aldehyde is favored relative to the same reaction at a ketone. 

As a result, abstraction of a hydrogen bound to carbon 6 (an alpha-carbon) is favored since the resulting carbanion may attack the aldehyde (carbon 1) to form a six-member ring, resulting in compound II. Compound I results from abstracting a hydrogen from carbon 2, generating a carbanion which may then attack the ketone. Based on the latter of the above principles, this is a minor product.

Example Question #653 : Organic Chemistry

What is the final organic product of the reaction shown?

Screen shot 2015 11 13 at 2.54.29 pm

Screen shot 2015 11 13 at 2.54.56 pm

Possible Answers:

I

IV

III

II

V

Correct answer:

I

Explanation:

First step: Friedel-Crafts acylation of benzene

Second step: Formation of enolate

Third step: aldol addition (enolate attacks carbonyl carbon in benzaldehyde)

Fourth step: neutralization of anion and dehydration forming alkene

Learning Tools by Varsity Tutors